linux-kernel - [PATCH] x86/intel: Fix always false range check in x86

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Message-ID: <20250728180923.160966-1-suchitkarunakaran@gmail.com>
Date: Mon, 28 Jul 2025 23:39:23 +0530
From: Suchit Karunakaran <suchitkarunakaran@...il.com>
To: tglx@...utronix.de,
	mingo@...hat.com,
	bp@...en8.de,
	dave.hansen@...ux.intel.com,
	hpa@...or.com,
	darwi@...utronix.de,
	sohil.mehta@...el.com,
	peterz@...radead.org,
	ravi.bangoria@....com
Cc: skhan@...uxfoundation.org,
	linux-kernel-mentees@...ts.linux.dev,
	linux-kernel@...r.kernel.org,
	Suchit Karunakaran <suchitkarunakaran@...il.com>
Subject: [PATCH] x86/intel: Fix always false range check in x86_vfm model matching

Fix a logic bug in early_init_intel() where a conditional range check:
    (c->x86_vfm >= INTEL_P4_PRESCOTT && c->x86_vfm <= INTEL_P4_WILLAMETTE)
was always false due to (PRESCOTT) being numerically greater than the
upper bound (WILLAMETTE). This triggers: -Werror=logical-op: 
logical ‘and’ of mutually exclusive tests is always false
The fix corrects the constant ordering to ensure the range is valid:
    (c->x86_vfm >= INTEL_P4_WILLAMETTE && c->x86_vfm <= INTEL_P4_PRESCOTT)

Signed-off-by: Suchit Karunakaran <suchitkarunakaran@...il.com>
---
 arch/x86/kernel/cpu/intel.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c
index 076eaa41b8c8..3ec1555cbdc3 100644
--- a/arch/x86/kernel/cpu/intel.c
+++ b/arch/x86/kernel/cpu/intel.c
@@ -262,7 +262,7 @@ static void early_init_intel(struct cpuinfo_x86 *c)
 	if (c->x86_power & (1 << 8)) {
 		set_cpu_cap(c, X86_FEATURE_CONSTANT_TSC);
 		set_cpu_cap(c, X86_FEATURE_NONSTOP_TSC);
-	} else if ((c->x86_vfm >= INTEL_P4_PRESCOTT && c->x86_vfm <= INTEL_P4_WILLAMETTE) ||
+	} else if ((c->x86_vfm >= INTEL_P4_WILLAMETTE && c->x86_vfm <= INTEL_P4_PRESCOTT) ||
 		   (c->x86_vfm >= INTEL_CORE_YONAH  && c->x86_vfm <= INTEL_IVYBRIDGE)) {
 		set_cpu_cap(c, X86_FEATURE_CONSTANT_TSC);
 	}
-- 
2.50.1